KR20090102272A - Method and apparatus for transmitting/receiving a control channel in a broadband wireless commmunication system and method for setting up a control channel candidate - Google Patents

Abstract

PURPOSE: A method and an apparatus for transmitting/receiving a control channel in a broadband wireless communication system and a method for setting up a control channel candidate are provided to prevent the occurrence of a signaling overhead without an additional signaling for the definition of PDCCH candidates for each user. CONSTITUTION: A method for transmitting/receiving a control channel in a broadband wireless communication system comprises the steps of: determining an input value of a hash function by performing the calculation depending on the sub-frame number of terminal identifiers; determining the candidates for a control channel in each level by applying the determined input value to the hash value(710); and transmitting the selected a modulated symbol string through the control channel candidate in the control channel candidate group(716).

Description

METHOD AND APPARATUS FOR TRANSMITTING / RECEIVING A CONTROL CHANNEL IN A BROADBAND WIRELESS COMMMUNICATION SYSTEM AND METHOD FOR SETTING UP A CONTROL CHANNEL CANDIDATE}

The present invention relates to a method and apparatus for transmitting and receiving a control channel in a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving a downlink control channel in a broadband wireless communication system.

The mobile communication system is evolving into a high speed, high quality wireless packet data communication system for providing data service and multimedia service, instead of providing a voice-oriented service in the early days. Recently, various mobile communication standards such as 3GPP's High Speed Downlink Packet Access (HSDPA), HSUPA (High Speed Uplink Packet Access), 3GPP2's High Rate Packet Data (HRPD), and IEEE's 802.16 are high-speed, high-quality wireless packet data transmission services. Was developed to support it.

Existing third generation wireless packet data communication systems such as HSDPA, HSUPA, HRPD, etc. use techniques such as Adaptive Modulation and Coding (AMC) and channel sensitive scheduling to improve transmission efficiency. By using the AMC method, the transmitter can adjust the amount of data to be transmitted according to channel conditions. In other words, if the channel condition is bad, the amount of data to be transmitted can be reduced to a desired level, and if the channel condition is good, the amount of data to be transmitted can be increased so that a large amount of information can be effectively transmitted while the reception error probability is set to a desired level. By using the channel sensitive scheduling resource management method, the transmitter selectively services a user having a good channel condition among multiple users, thereby increasing system capacity compared to allocating and serving a channel to one user. This increase in capacity is called the multi-user diversity gain. In short, the ACM method and the channel sensitive scheduling method are methods of applying an appropriate modulation and coding scheme at a time when it is determined to be the most efficient by receiving partial channel state information from a receiver.

Recently, studies are being actively conducted to convert CDMA (Code Division Multiple Access), which is used in second and third generation mobile communication systems, to orthogonal frequency division multiple access (OFDMA) in a next generation system. 3GPP and 3GPP2 have begun standardizing on evolutionary systems using OFDMA. It is known that the capacity can be increased in the OFDMA method as compared to the CDMA method. One of various causes of capacity increase in the OFDMA scheme is that frequency domain scheduling can be performed on the frequency axis. Just as the channel gains capacity gains through channel-sensitive scheduling as the channel changes over time, more capacity gains can be achieved if the channel utilizes different characteristics depending on frequency.

By implementing the ACM method and the channel sensitive scheduling method, the base station adaptively allocates a given radio resource such as frequency, time, power, etc. according to the user's channel state. This adaptive allocation state is transmitted by the base station to the user through the PDCCH and the user is aware of which radio resources are allocated to the user through the PDCCH reception.

Radio resource allocation includes a downlink resource allocation transmitted by the base station and received by each user terminal and an uplink resource allocation transmitted by the user terminal and received by the base station. Downlink resource allocation is adaptively performed according to the channel status reported by the user and the amount of information of the data to be transmitted to the user by the base station. The data is transmitted by assigning which resource to which user through the PDCCH. What is the transmission method such as the method? The user terminal knows how to receive a signal transmitted through the allocated resource if the downlink resource is allocated to the user terminal based on the PDCCH information. The uplink resource allocation is adaptively made based on the channel status reported by the user and the amount of information to be transmitted. The PDCCH transmits data to which resource is allocated to which user and which resource is allocated by using a transmission method. Tell them what to do The user terminal recognizes which transmission scheme should be used if an uplink resource is allocated or allocated to the user terminal based on the information of the PDCCH.

The information included in the PDCCH for downlink resource allocation (hereinafter, referred to as DCI) is generally as follows.

UE ID: UE ID is information for identifying whether there is a signal transmitted to the UE. In general, since a CRC (Cyclic Redundancy Check) according to a specific UE ID is inserted into the DL control information, if the terminal successfully restores the DL control information, the control information is recognized as information for the corresponding terminal.

Downlink Resource Block (DL RB) allocation information: If the UE successfully restores DL control information, the UE recognizes to which resource block its actual data is transmitted through the DL RB information.

Transport Format (TF): A TF represents a modulation and coding scheme of a transmitted signal. If AMC is applied, the terminal must know the TF to perform the demodulation and decoding process.

Hybrid Automatic Repeat request (HARQ) Related information: HARQ sends a transmitter to the transmitter whether or not the receiver has successfully received a transmission packet. Retransmits the previous packet. HARQ-related information means information related to HARQ, such as whether the transmission signal is the initial transmission or retransmission, HARQ process number, and the like. Based on this, the terminal may combine the current received packet with the previous received packet and perform a new decoding operation. Will be judged.

In addition, additional information for multi-antenna transmission, additional information for power control, additional information indicating whether distributed transmission may be included in the information included in the PDCCH, that is, DCI.

Information included in the PDCCH for uplink resource allocation is generally as follows.

UE ID

Uplink Resource Block (UL RB) allocation information: If the UE successfully restores the control information, the UE recognizes to which resource block to transmit data through the UL RB information.

Transport Format (TF): The terminal needs to know the TF to be applied to generate a transmission signal according to the demodulation and decoding scheme requested by the base station.

Information about hybrid automatic repeat request (HARQ)

In addition, uplink reference signal additional information for supporting uplink space multiple access, additional information indicating whether transmission is distributed, and additional information indicating whether channel status information is requested or not is included in the DCI. May be included.

As the mobile communication system evolved to the wideband OFDMA method, the amount of resources to be allocated increases, but the amount of resources to be used as a unit of allocation does not increase in proportion to the PDCCH transmitted simultaneously compared to the conventional mobile communication system. Increasing the number of is inevitable.

The terminal should attempt blind decoding in a candidate group in order to find what has been transmitted to itself among several downlink control channels. Here, the blind decoding means that the base station can transmit the PDCCH using one of the control channel candidates defined in the control channel candidate group, and the terminal receives without any prior information on which control channel candidate the control channel information is to be transmitted. do.

1 is a diagram illustrating a method for setting a control channel candidate group in a conventional broadband wireless communication system.

In FIG. 1, a control channel element (CCE) refers to a unit of a logical channel constituting the PDCCH. CCE has a one-to-one correspondence with a set of resource elements (REs), which are units of a physical channel. How many CCEs configure the PDCCH is called an aggregation level (AL). If PDCCH is configured with N CCEs, AL becomes N. In the example of FIG. 1, the collection level is AL = 1 (111), AL = 2 (112), AL = 4 (113), and AL = 8 (114). Consider the case where it is configured.

In the example of FIG. 1, it is assumed that the PDCCH uses one modulation scheme. In this case, as the vowel level decreases, the number of coded bits that can be transmitted decreases. This means that the channel code rate of the PDCCH is reduced. That is, the lower the vowel level, the less information can be used to transmit the control information, but the terminal can be successfully received only if the terminal is experiencing a good channel state. The higher the collection level, the more resources are used, while the terminal suffering from poor channel conditions can receive successfully. In order to effectively utilize resources, it is desirable to configure a control channel by lowering the vowel level in a terminal having a good channel state and increasing the vowel level in a terminal having a poor channel state.

The number of information bits constituting the DCI may vary depending on the property of the control information. For example, in marking resource block allocation information, many bits may be used to increase the degree of freedom, or the number of bits may be reduced instead of lowering the degree of freedom. The number of information bits constituting the DCI varies depending on whether to include various additional information. When DCI is configured with different numbers of bits, they are distinguished by the DCI format. Since the UE does not know in which DCI format the PDCCH is transmitted, this is also subject to blind decoding. Even when transmitting to the UE of the same channel state, it is preferable to transmit the PDCCH of the DCI format using many bits at a higher vowel level than the PDCCH of the DCI format using fewer bits.

Looking at the example of Figure 1 is given eight CCE (100 ~ 107). This is for convenience of explanation and the number of CCEs may change from time to time. Affecting the number of CCEs is a subframe that is a unit of time in which scheduling is performed and static values such as downlink system bandwidth, number of base station transmit antennas, number of downlink ACK / NACK channels for supporting uplink HARQ, and the like. ) Includes control region information whose value changes.

In the example of FIG. 1, PDCCH candidates corresponding to AL = 1 (111) are 120 to 127. Reference numeral 120 denotes a PDCCH configured using one CCE 0 (100), and reference numeral 127 denotes a PDCCH configured using one CCE 7 (107). PDCCH candidates corresponding to AL = 2 (112) include 128 and 129. Reference number 128 indicates that the PDCCH is configured using two CCE 0 (100) and CCE 1 (101). PDCCH candidates corresponding to AL = 4 (113) include 132 and the like, and reference numeral 132 denotes a PDCCH using four CCE 0 (100) to four CCE 3 (103). There are 134 PDCCH candidates corresponding to AL = 4 (114), and PDCCH is configured using 8 CCEs such as CCE 0 (100) to CCE 7 (107).

In the example of FIG. 1, the method of configuring PDCCH candidates for each vowel level is based on a tree structure. It consists of a collection of PDCCH candidates with AL = 1 in AL = 2, a collection of PDCCH candidates with AL = 2 in AL = 4, and a collection of PDCCH candidates with AL = 4 in AL = 8 . For example, reference numeral 132 denotes a PDCCH configured by collecting four CCEs of CCEs 0 to 3, which is a PDCCH candidate 128 collecting CCEs 0 and 1 and an PDCCH candidate 129 collecting CCEs 2 and 3 at AL = 2. According to this tree structure, when the total number of CCEs is N_CCE, the number of PDCCHs that can be configured at the collection level AL is floor (N_CCE / AL). Where floor (x) is a truncation function representing the maximum integer less than or equal to x.

If the terminal needs to decode all PDCCH candidates, blind decoding should be performed on N_CCE + floor (N_CCE / 2) + floor (N_CCE / 4) + floor (N_CCE / 8) PDCCH candidates. The terminal must perform an appropriate transmission / reception operation according to the control information indicated by the PDCCH. Before performing this operation, the terminal should receive the PDCCH transmitted to the terminal. The terminal should be designed in consideration of the maximum number of decoding attempts so as not to miss the PDCCH transmitted to it. As described above, the maximum number of decoding attempts of the PDCCH increases in proportion to N_CCE. For example, if N_CCE = 32, blind decoding must be performed for AL = 1 to 32 times, AL = 2 to 16 times, AL = 4 to 8 times, and AL = 8 to 4 times. Given too much blind decoding, the receiving complexity of the terminal will increase and the price will increase. For effective blind decoding management, it is necessary to limit the maximum number of blind decoding attempts. This can be achieved by setting a PDCCH candidate group to be decoded for each terminal. The size of the PDCCH candidate group is determined by the maximum number of blind decoding attempts. As such, when the PDCCH candidate group is restricted for each terminal, some terminals will share the same PDCCH candidate. If one user occupies a specific PDCCH candidate, another PDCCH candidate using a CCE belonging to this PDCCH candidate cannot be used for PDCCH transmission of another user. Therefore, the PDCCH candidate group needs to be defined appropriately for each user.

The present invention provides a method and apparatus for transmitting and receiving a control channel in a broadband wireless communication system and a method for setting a control channel candidate group therefor.

The present invention also provides a method and apparatus for transmitting and receiving a downlink control channel in a broadband wireless communication system and a method for setting a control channel candidate group for each user.

The present invention also provides a method and apparatus for transmitting and receiving a downlink control channel that can reduce the number of decoding attempts of a terminal in a broadband wireless communication system, and a method for setting a control channel candidate group therefor.

A method for transmitting a control channel in a broadband wireless communication system according to the present invention includes: performing an operation according to a subframe number on a terminal identifier to determine an input value of a hash function; Determining a control channel candidate group for each vowel level by applying the determined input value to the hash function; And transmitting a modulated symbol sequence through a control channel candidate selected from the control channel candidate group.

In addition, a method of receiving a control channel in a broadband wireless communication system includes: performing an operation according to a subframe number on a terminal identifier to determine an input value of a hash function; Determining a control channel candidate group for each vowel level by applying the determined input value to the hash function; And performing decoding for each control information format that can be received for the control channel candidate group.

As described above, according to the present invention, first, separate signaling is not required to define a PDCCH candidate group for each user. Therefore, no signaling overhead occurs.

Second, the PDCCH candidate group changes for each subframe. Therefore, even if different users share the same PDCCH candidate group in one subframe and CCEs of PDCCH candidates are preempted by other users, a specific user may not be scheduled. This problem may be solved in the next subframe.

Third, the amount of computation required for the hash function that defines the PDCCH candidate group is very small. In the process of determining X, a simple structure such as bit-wise permutation or cyclic shift is employed, and the intrinsic function is also defined as a linear function, so the complexity is very low.

Fourth, the hash function proposed in the present invention has a characteristic that the PDCCH candidate group is randomly determined if the UEID is randomly determined. The PDCCH candidate group must be randomly determined in order for the PDCCH candidate group collisions between different users to have certain statistical characteristics. In the present invention, since the PDCCH candidate group is determined by manipulating the bit string of the UEID, the random characteristic of the UEID guarantees the random characteristic of the PDCCH candidate group.

1 is a view showing a method for setting a control channel candidate group in a conventional broadband wireless communication system,

2 is a view showing a method for setting a control channel candidate group in a broadband wireless communication system according to a first embodiment of the present invention;

3 is a diagram illustrating an operation of bit-wise permutation of a UEID in a method for setting a control channel candidate group according to the first embodiment of the present invention;

4 is a diagram illustrating a method for setting a control channel candidate group in a broadband wireless communication system according to a second embodiment of the present invention;

5 is a diagram illustrating an operation of performing a bit-wise cyclic shift in a method of setting a control channel candidate group according to a second embodiment of the present invention;

6 is a flowchart illustrating a method for transmitting a control channel by a base station in a wireless communication system according to the present invention;

7 is a flowchart illustrating a method in which a terminal receives a control channel in a wireless communication system according to the present invention;

8 is a block diagram showing the configuration of a base station for transmitting a control channel in a broadband wireless communication system according to the present invention;

9 is a block diagram showing a configuration of a terminal receiving a control channel in a broadband wireless communication system according to the present invention.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The present invention provides a method for setting an appropriate PDCCH candidate group for each user for efficient blind decoding management. To this end, the PDCCH candidates collide with each other, and as a user preempts a specific PDCCH, the probability that another user cannot be scheduled is reduced, and if such a situation occurs, the conflicting users are different PDCCH candidates in the next subframe. You should make sure that the problem does not persist by making it available. In this case, a method of externally notifying the PDCCH candidate group for each user is not preferable in terms of increasing signaling overhead. Accordingly, the present invention proposes a method of setting a PDCCH candidate group using a hash function so that the PDCCH candidate group can be set inherently. Here, the implicit method means setting up the PDCCH candidate group so that the base station and the terminal can share the PDCCH candidate group according to a predetermined rule without additional signaling. The external method means that the base station and the terminal share the PDCCH candidate group through separate signaling. It means that the PDCCH candidate group to be set.

The present invention proposes a hash function for setting a PDCCH candidate group for each terminal. In the method of setting the PDCCH using the hash function, a PDCCH candidate group is designated by using a UEID which is a unique value for each terminal. Here, the hash function is defined for each collection level, and a plurality of PDCCH candidates in the collection level are determined based on the output of the hash function. That is, the present invention proposes a hash function that defines a PDCCH candidate group according to UEID and subframe number for efficient blind decoding management. Some users may share the same PDCCH candidate. The subframe number is used as the input of the hash function to design the hash function so that PDCCH candidates can be determined differently for each subframe so that this situation does not persist. That is, the input of the hash function is the number of PDCCH candidates per UEID, subframe number, collection level, and collection level.

The hash function proposed in the present invention has the form as shown in Equation 1 below.

Y = {a * X (UEID, suframe_number) + c} mod m

X is a variable determined by UEID and subframe number. The number of cases of X that can be made by the combination of UEID and subframe number is very large compared to the number of PDCCH candidates. The hash function is a function that determines a PDCCH candidate using such a large range of inputs. In Equation 1, m represents the number of PDCCH candidates at a corresponding vowel level. When the collection level is AL and the number of CCEs is N_CCE, the number of PDCCH candidates is floor (N_CCE / AL). mod stands for modular operation, where x mod y is the remainder of x divided by y. And a and c are parameters of hash function that can be defined differently according to collection level.

The output Y of the hash function of Equation 1 refers to the number of the first PDCCH candidate selected at the corresponding vowel level. If a plurality of PDCCH candidates are defined at the vowel level, the remaining PDCCH candidates may be determined using the output Y.

Equation 2 below shows how N_AL PDCCH candidates are determined at the vowel level AL using Y obtained from Equation 1 below.

S [k] = {((Y + k * Δ) * AL) mod N_CCE, ..., ((Y + k * Δ + 1) * AL-1) mod N_CCE}, for k = 0, .. ., N_AL-1

S [k] is a set of CCE numbers constituting the (k + 1) th PDCCH candidate, and the number of elements is AL. The first PDCCH candidate (k = 0) is composed of AL CCEs whose CCE numbers are from (Y * AL) to ((Y + 1) * AL-1). That is, Y indicates how to configure the first PDCCH candidate. In the process of describing the operation of Equation 2, the mod operation is omitted for convenience. The second PDCCH candidate becomes a PDCCH candidate separated by Δ (> 0) based on the first PDCCH candidate. If Δ = 1, the second PDCCH candidate (k = 1) consists of CCEs with CCE numbers ranging from ((Y + 1) * AL) to ((Y + 2) * AL-1), which are the first PDCCH candidates. The following are the CCEs. If the value of Δ is large, the PDCCH candidates are separated from each other. When a continuous PDCCH candidate is set for a user A due to a vowel level characteristic having a tree structure, some of the plurality of PDCCH candidates may share a CCE belonging to one of the higher collection level PDCCH candidates assigned to another user B. In this case, when user B preempts a higher collection level PDCCH candidate, user A cannot find an available PDCCH. To avoid this, it may be necessary to set Δ large. For example, in FIG. 1, user A is supposed to use two PDCCH candidates of 120 and 121 at AL = 1, and user B is to use one P128CH candidate of 128 at AL = 2. If user B preempts 128, CCE 0 (100) and CCE 1 (101) belonging to the resource are resources that cannot be used by other users. However, user A cannot be scheduled because only 120 and 121 have been allocated using them. However, if user A does not allocate consecutive PDCCH candidates 120 and 121 without assigning consecutive PDCCH candidates 120 and 122, user B can preempt 128 and use 122 even though the PDCCH candidate 120 cannot be used.

The hash function proposed in the present invention consists of two processes. The first process is to determine the variable X using the UEID and subframe number, and the second process is to determine Y by using Y = f (X) = {a * X + c} mod m using this X. It is the process of obtaining. Here, f (X), which corresponds to the second process, is called a built-in function to distinguish it from the entire hash function.

The present invention proposes two embodiments as the first process for determining X. The first embodiment utilizes bit-wise permutation and the second embodiment utilizes bit-wise cyclic shift.

FIG. 2 is a diagram illustrating a method for setting a control channel candidate group in a broadband wireless communication system according to a first embodiment of the present invention, wherein the first embodiment uses bit-wise permutation to determine the variable X. FIG. It is characterized by using.

First, permutation pattern generator 204 determines permutation pattern 206 according to subframe number 202 according to the command of controller 216. Here, the permutation pattern may retrieve a value calculated by a specific function or stored in a memory (not shown). The variable X 212 is obtained by bit-wise permutation of the UEID 208 in the permutation apparatus 210 using this permutation pattern. The controller 216 receives the number 214 of the PDCCH candidates or the variables determining the number of the PDCCH candidates, and passes the parameters 218 such as a, c, Δ, and m to the intrinsic function 220. Built-in function 220 finds Y 222 using variable X 212 and parameter 218. Here, the output Y of the hash function refers to the number of the first PDCCH candidate selected at the corresponding vowel level. Hash function 200 in Figure 2 refers to this overall operation.

3 is a diagram illustrating an operation 210 for bit-wise permutation of the UEID 208 in the method for setting a control channel candidate group according to the first embodiment of the present invention.

In FIG. 3, it is assumed that the UEID is composed of a0 to a15 16bits 300. Bit-wise permutation is to shuffle these 16-bit positions. Reference numeral 302 denotes a result in which UEIDs are mixed through bit-wise permutation. Permutation pattern 206 shows how to shuffle the bits of the UEID. The feature of the hash function of the first embodiment is that the permutation pattern varies with the subframe number. That is, as a result of mixing the UEID 16bits (300), the mixed UEID (302) is changed for each subframe. When the built-in function 22 is applied to the variable X 212 obtained by bit-wise permutation of the UEID 208, a different Y value can be obtained for each subframe.

FIG. 4 is a diagram illustrating a method for setting a control channel candidate group in a broadband wireless communication system according to a second embodiment of the present invention. The second embodiment is a bit-wise cyclic transition for determining the variable X. FIG. shift). Using the UEID 208 and the subframe number 202, the cyclic shift device 400 obtains the variable X 402 by bit-wise cyclic shifting the UEID. Meanwhile, in FIG. 4, the controller 216 receives the number 214 of PDCCH candidates or the variables determining the number of the PDCCH candidates, and passes parameters 218 such as a, c, Δ, and m values to the intrinsic function 220. do. Referring to the operation of the cyclic shift device 400 in the following equation (3).

X = cyclic_shift (UEID, shift (subframe_number))

Here, the cyclic_shift function represents a function of bit-wise cyclic shifting of the UEID by shift. An embodiment of a bit-wise cyclic shift operation is shown in FIG. A bit-wise cyclic shift of the UEID 16bit (300) by shift = 4 is (510). In Equation 3, the shift value is determined by the subframe number. How the shift value is determined using the subframe number, that is, the shift () function is determined by the controller 216 of FIG. The controller 216 receives a number 214 of PDCCH candidates or variables that determine the number of PDCCH candidates to determine a shift () function to be used in the cyclic shift device 400. The built-in function 220 obtains Y 404 using the variable X 402 of bitwisewise shifting the UEID 208. As in the first embodiment, built-in function 220 finds Y 404 using parameter 218 determined by controller 216.

One example of the function shift () used in Equation 3 may include shift (x) = q * x. Q is a constant determined by the number of bits of the UEID and the value of m in Equation 1, and an integer greater than log2 (m) and not divided by the prime factor of the number of bits of the UEID is selected as the value of q. Assuming that the UEID is composed of 16 bits, the following values can be selected as q according to the range of m.

m≤4 ===> q = 3

4 <m≤16 ===> q = 5

16 <m≤64 ===> q = 7

64 <m≤128 ===> q = 9

The shift () function using the q value may be used by defining another type of function in one embodiment.

Bit-wise cyclic shift is a special example of bit-wise permutation. Therefore, the second embodiment can be said to be a special example of the first embodiment.

6 is a flowchart illustrating a method for transmitting a control channel by a base station in a wireless communication system according to the present invention.

The base station first determines the priority of the user to be scheduled in step 600. In operation 602, the DCI and DCI format of the user to be scheduled are determined in order of priority. In step 604, the base station calculates the number of available CCEs in the corresponding subframe. The number of available CCEs is a control region where the static values such as the downlink system bandwidth, the number of base station transmit antennas, the number of downlink ACK / NACK channels for supporting uplink HARQ, and the subframes that are the unit of scheduling time are changed. (control region) information or the like. In step 606, the number m of PDCCH candidates is determined for each vowel level. This value is used in the controller 216 to calculate the parameters of the intrinsic function 220 or in the intrinsic function 220 of Equation 1 above. Step 608 is a process of determining a candidate PDCCH group by applying the hash function proposed in the present invention. Step 608 consists of steps 610 and 612. In step 610, it is the first process of the hash function for calculating the input X of the built-in function 220 by applying a cyclic shift or permutation according to the subframe number to the UEID bit string. In operation 610, a method of obtaining X from the UEID is to apply permutation according to the first embodiment and to apply cyclic shift according to the second embodiment. In step 612, the built-in function f (x) is performed to obtain Y for each vowel level. When Y is obtained, a PDCCH candidate is determined according to Equation 2 above. In step 614, a PDCCH candidate that is not occupied by a user having a higher priority is selected. The selected PDCCH candidate is determined as the PDCCH of the corresponding user, and in step 616, a symbol sequence obtained by channel encoding and modulating the DCI according to the DCI format is mapped to the selected PDCCH. In step 618, the PDCCHs of all scheduled users are completed by repeating steps 604 to 616 for the users to be scheduled next. In operation 620, the DL data signal is multiplexed with the DL data signal and then transmitted.

7 is a flowchart illustrating a method in which a terminal receives a control channel in a wireless communication system according to the present invention.

Each user terminal identifies a DCI format that can be received in step 700. Receivable DCI format is previously set through higher signaling. In step 702, the number of available CCE is calculated. As shown in the transmission sequence of the base station of FIG. 6, the number of available CCEs is determined by static values such as downlink system bandwidth, number of base station transmit antennas, number of downlink ACK / NACK channels for supporting uplink HARQ, and the like. Since the terminal is determined by control region information whose value changes for each subframe, which is a time unit, the terminal should receive and grasp all these values. In step 704, the number of PDCCH candidates m is determined for each collection level. This value is used in the controller 216 to calculate the parameters of the intrinsic function 220 or in the intrinsic function 220 of Equation 1 above. Step 706 is a process of determining a candidate PDCCH group by applying the hash function proposed in the present invention. Step 706 is composed of steps 708 and 710. In step 708, this is the first process of the hash function for calculating the input X of the built-in function 220 by applying a cyclic shift or permutation according to the subframe number to the UEID bit string. In operation 708, a method for obtaining X from the UEID is to apply permutation according to the first embodiment and to apply cyclic shift according to the second embodiment. In step 710, the built-in function f (x) is performed to obtain Y for each vowel level. When Y is obtained, a PDCCH candidate is determined according to Equation 2 above. In step 712, after demodulating the PDCCH candidates obtained in step 706, channel decoding is performed for each DCI format that can be received. In step 714, CRC check is performed to determine whether the decoding succeeds. If decoding fails, step 712 is repeated for another PDCCH candidate obtained through step 706. If decoding is performed on all PDCCH candidates but all of the decoding fails, it is determined that there is no PDCCH transmitted to the corresponding user. If the PDCCH decoding is successful in step 714, the transmission / reception operation is performed according to the DCI information transmitted through the PDCCH.

8 is a block diagram showing the configuration of a base station for transmitting a control channel in a broadband wireless communication system according to the present invention.

In FIG. 8, the base station scheduler 800 determines which user allocates a downlink resource or an uplink resource by transmitting a PDCCH, and assigns priority to each user. The base station scheduler 800 performs this task based on the channel status reported by each user. Controller 802 controls the operation of each other device based on scheduler 800 determination. Depending on the determination of the controller 802, the decision of the scheduler 800 may be updated. The process proposed by the present invention is performed in the apparatus 804 for performing the PDCCH hash function. The device receives instructions from the controller 802 for parameters of an intrinsic function, the number of available CCEs, the number of available PDCCH candidates, and the method of determining X, and determines a PDCCH candidate and sends the value back to the controller 802. . The decision of the scheduler 800 is translated into DCI via the controller 802. The DCI signal generator 806 receives the DCI from the controller 802 and generates a DCI signal. The signal is transmitted on a PDCCH selected by the controller 802 among the PDCCH candidate groups determined by the PDCCH hash function device 804. This process is performed in the CCE mapping apparatus 808. Meanwhile, the downlink data signal is multiplexed with the PDCCH signal through channel encoding and modulation process 812. The downlink signal is transmitted through a transmission process 816.

9 is a block diagram showing the configuration of a terminal receiving a control channel in a broadband wireless communication system according to the present invention.

In FIG. 9, the received signal is converted into a baseband signal through a reception process 900 and divided into a data signal and a control signal through a demultiplexer 902. The control signal is demultiplexed for each PDCCH candidate through the CCE de-mapping apparatus 904. The process proposed by the present invention is performed in the apparatus 904 for performing the PDCCH hash function. The device 904 receives instructions from the controller 908 such as the parameters of the intrinsic function, the number of available CCEs, the number of available PDCCH candidates, and the method of determining X. Send it back. The controller 908 informs the CCE de-mapping apparatus 904 of the PDCCH candidates. The channel decoder / demodulator 906 performs demodulation and decoding for each PDCCH candidate to inform the controller 908 of the success of the decoding. If decoding fails for a particular PDCCH candidate, the controller 908 allows processing through the CCE de-mapping 904 and the channel decoder / demodulator 906 and 906 for the other PDCCH candidate. Meanwhile, the controller 908 determines whether there is a downlink data signal transmitted to the corresponding user through successful decoding of the PDCCH, and demodulates and decodes the data signal extracted by the demultiplexer 902.

Claims (6)

A method for transmitting a control channel in a broadband wireless communication system, Determining an input value of a hash function by performing an operation according to a subframe number on the terminal identifier; Determining a control channel candidate group for each vowel level by applying the determined input value to the hash function; And And transmitting a modulated symbol string through a control channel candidate selected from the control channel candidate group. The method of claim 1, And wherein said operation replaces the bit string of said terminal identifier with said subframe number. The method of claim 1, And wherein said operation cyclically shifts the bit string of said terminal identifier according to said subframe number. A method for receiving a control channel in a broadband wireless communication system, Determining an input value of a hash function by performing an operation according to a subframe number on the terminal identifier; Determining a control channel candidate group for each vowel level by applying the determined input value to the hash function; And And performing decoding for each control information format that can be received for the control channel candidate group. The method of claim 4, wherein And wherein said operation replaces a bit string of said terminal identifier with said subframe number. The method of claim 4, wherein And wherein said operation cyclically shifts the bit string of said terminal identifier according to said subframe number.